Is this just one freak year? Or is this global warming? Few scientists are willing to blame global warming, the theory that carbon dioxide and other manmade emissions are trapping heat in the Earth's atmosphere and causing a worldwide rise in temperatures. Yet few are willing to rule it out.
"There are strange things happening, but we don't really understand how all the pieces fit together," said Jane Lubchenco, a zoologist and climate change expert at Oregon State University.
"It's hard to say whether any single event is just an anomaly or a real indication of something serious happening."
Scientists say things could very well swing back to normal next year. But if the phenomenon proves to be long-lasting, the consequences could be serious for birds, fish and other wildlife.
This much is known: From California to British Columbia, unusual weather patterns have disrupted the marine ecosystem.
Normally, in the spring and summer, winds blow south along the Pacific Coast and push warmer surface waters away from shore. That allows colder, nutrient-rich water to well up from the bottom of the sea and feed microscopic plants called phytoplankton.
Phytoplankton are then eaten by zooplankton, tiny marine animals that include shrimp-like crustaceans called krill. Zooplankton, in turn, are eaten by seabirds and by fish and marine mammals ranging from sardines to whales.
But this year, the winds have been unusually weak, failing to generate much upwelling and reducing the amount of phytoplankton.
Off Oregon, for example, the waters near the shore are 5 to 7 degrees warmer than normal and have yielded about one-fourth the usual amount of phytoplankton, said Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration in Newport, Ore.